Exergetic investigation and Taguchi-based optimization of a modified passive solar still augmented with nano-PCM & fins

This study investigates the efficacy of integrating a nano-enhanced heat storage system along with fins to enhance the performance of the Double Slope Passive Solar Still (DS-SS) in the meteorological conditions of Bareilly, India (28.367 degrees N, 79.43 degrees E). The research approach combines experimental and statistical methods to validate the effectiveness of this system. Furthermore, an exergy-based analysis is conducted to identify potential sources of exergy losses in the system. To design the experiments efficiently, a Taguchi-based L9 orthogonal array is developed using MINITAB software, wherein three key factors are considered as control parameters: the concentration of nano particles, the number of fins, and the water-depth in the basin. The analysis of the signal-to-noise ratio, ANOVA and regression analysis indicate that the concentration of nano-particles emerges as a critical parameter, exerting 74.29% contribution in improving the yield of the heat augmented DS-SS. Modified solar still (M-SS) reflected the highest gain of 86.4%, 41.18%, and 59.54% in daily accumulated yield, rysh and ry,,, respectively over the conventional solar still (C-SS). M-SS demonstrated remarkable improvements in exergy flow rates and heat transfer coefficients for convection, showing a substantial daily average gain of 109.46% and 35.64%, respectively. Additionally, it exhibited impressive results in the context of evaporation, with gains of 136.97% in exergy flow rates and 37.27% in heat transfer coefficients. Enhanced sustainability index and low waste exergy ratio makes M-SS more environment friendly. In trial 9, during adverse meteorological conditions, the heat storage capability of M-SS was evident. It showed a 1.05% times higher SI and a 4.89% lower IP compared to C-SS. The cost analysis of M-SS is also in close agreement to the C-SS.